Many prescriptions for eye drops call for instillation of 1-2 drops. But Medical Letter consultants in ophthalmology seem to agree that all eye drops should generally be given in doses of only one drop. The volume of a single drop can vary with the viscosity of the solution, the design of the dropper, and patient technique. The average volume of a drop is 35-50 microliters, but can be as high as 75 microliters. An eye brimming with fluid holds 30 microliters at best, so even one drop is often an overdose. A second either washes out the first or increases the possibility of systemic toxicity,...

The gram-positive anaerobic bacillus Clostridium difficile is the most common identifiable cause of antibiotic-associated diarrhea. The antibiotics most often implicated have been ampicillin, second and third generation cephalosporins, clindamycin and fluoroquinolones. The emergence in recent years of a new, more toxic epidemic strain (BI/NAP1), possibly related to widespread use of fluoroquinolones, has caused a marked increase in the incidence and severity of C. difficile-associated disease (CDAD).

Rotigotine (Neupro - Schwarz Pharma), a nonergot dopamine agonist in a transdermal patch formulation, was recently approved by the FDA for treatment of early Parkinson's disease (PD).

Clopidogrel (Plavix - Sanofi-Aventis and Bristol-Myers Squibb), an oral thienopyridine that inhibits platelet aggregation, is now being advertised directly to the public on television. Clopidogrel is approved by the FDA for secondary prevention of myocardial infarction (MI), stroke and other vascular events and for use in patients with acute coronary syndrome (unstable angina or non-ST-elevation MI), including those undergoing angioplasty. It is used off-label for patients with ST-elevation acute MI

Rasagiline (Azilect - Teva), a monoamine oxidase-type B (MAO-B) inhibitor, was recently approved by the FDA for once-daily oral treatment of Parkinson's disease (PD). It can be taken alone for treatment of early disease or with levodopa/carbidopa (Sinemet, and others) for advanced disease. Selegiline (Eldepryl, and others), the first MAO-B inhibitor marketed in the US, has been available since 1988; a new lower-dose disintegrating tablet (Zelapar) was recently approved.

Levocetirizine (Xyzal - UCB/Sanofi-aventis), the active enantiomer of the second-generation H₁-antihistamine cetirizine (Zyrtec), has been approved by the FDA for treatment of seasonal and perennial allergic rhinitis (SAR and PAR) and chronic idiopathic urticaria in adults and children 6 years of age and older. Cetirizine has been approved by the FDA for over-the-counter use and may also become available generically in the US. Levocetirizine has been available in Europe since 2001.

Liraglutide (Victoza – Novo Nordisk), a glucagon-like peptide-1 (GLP-1) receptor agonist given by subcutaneous injection, has been approved by the FDA for treatment of patients with type 2 diabetes. It can be used alone or in addition to oral antidiabetic drugs such as metformin (Glucophage, and others) or glimepiride (Amaryl, and others). Liraglutide is not recommended for first-line therapy and is not approved for use with insulin.

Age-related macular degeneration (AMD) has two major forms: dry or non-neovascular (~90% of patients) and wet or neovascular (~10% of patients).

Antiretroviral therapy is recommended for all HIV-infected patients, both to reduce the risk of disease progression and to prevent transmission of the virus to others. Various guidelines for treatment of HIV infection are available.

The text that follows reviews some common bacterial infections and their empiric treatment pending the results of culture and susceptibility testing. The recommendations made here are based on the results of susceptibility studies, clinical trials, and the opinions of Medical Letter reviewers. Tables 1 and 2 list the usual dosages of antibacterial drugs.